Antennas with dipole radiating elements (dipoles), both low frequency band (“low band” or “LB”) and high frequency band (“high band” or “HB”), are commonly used in the communications industry. Conventional dipoles, such as half wavelength dipoles with V-shaped, U-shaped, “butterfly”, “bow tie” or “four square” arm structures are described in several known publications.
Particularly, panel-type base station antennas, such as those used in mobile communication systems, are often dual polarization antennas. That is, these antennas often radiate radio frequency (RF) signals/energy on two opposite polarizations. Most dual polarization antennas are made with dual polarized elements, either by including a single patch element fed in such a manner to create a dual polarized structure, or by combining two linear polarized dipoles into one, thereby making a single, dual polarization element.
Conventional, dual polarization dipole radiating elements often have problems with beam width stability. It is, therefore, desirable to provide antennas with dipole radiating elements having improved beam width stability.
Additionally, many conventional panel-type base station antennas are multi-band (e.g., dual band or triple band) antennas. These antennas are configured to operate in two or more frequency bands, often with one or more groups or columns of dipole radiating elements operating within a low frequency range, and one or more groups or columns of dipole radiating elements operating in a high frequency band. In such antennas, there are often problems with resonance from high band dipole radiating elements creating interference with low band frequencies. It is therefore desirable to provide antennas with reduced low band interference due to resonance from high band radiating elements.
It is further desirable to improve cross-polarization (ratio of power in a desired polarization to power in the opposite polarization) in dipole antennas.
Still further, antennas that include a plurality of dipole radiating elements may experience issues with poor isolation between adjacent radiating elements. It is, therefore, desirable to provide features that improve isolation between opposite polarities of adjacent radiating elements in antennas.
It is further desirable to provide antennas having the aforementioned benefits that are easy and cost-effective to manufacture.